A cowling of a motorcycle is often formed by combining a plurality of cowling members having different properties such as material so that a single cowling may consist of different parts having different colors and/or made of different materials. Screw fasteners and bonding agents are most commonly used for joining together different cowling members. It has also been proposed to form a cowling fastening structure in which a first trim part and a second trim part project from two cowling members, respectively, and with the first and second trim parts engaged (form-fitted) with each other, the two trim parts are clamped by a U-shaped clip (clamp) having a pair of clamping pieces. See Patent Document 1.